Highly dispersible carbon nanospheres in an organic solvent and methods for making same

ABSTRACT

The particle sizes of agglomerates of carbon nanospheres are reduced by dispersing the carbon nanospheres in an organic solvent. The carbon nanospheres are multi-walled, hollow, graphitic structures with an average diameter in a range from about 10 nm to about 200 nm, more preferably about 20 nm to about 100 nm. Spectral data shows that prior to being dispersed, the carbon nanospheres are agglomerated into clusters that range in size from 500 nm to 5 microns. The clusters of nanospheres are reduced in size by dispersing the carbon nanospheres in an organic solvent containing at least one heteroatom (e.g., NMP) using ultrasonication. The combination of organic solvent and ultrasonication breaks up and disperses agglomerates of carbon nanospheres.

BACKGROUND OF THE INVENTION

1. The Field of the Invention

The present invention relates generally to the manufacture of carbonnanomaterials. More particularly, the present invention relates tomethods for manufacturing carbon nanospheres that are highly dispersedin an organic solvent.

2. The Related Technology

Carbon materials have been used in various fields for a variety ofapplications. Examples of current uses of carbon materials includepigments, fillers, catalyst supports, and fuel cell electrodes, amongothers. Pyrolysis of organic compounds is a known method for preparingcarbon materials. For example, carbon materials can be produced bypyrolyzing resorcinol-formaldehyde gel at temperatures above 600° C.

Most carbon materials obtained by pyrolysis of organic compounds attemperatures between 600-1400° C. tend to be amorphous or have adisordered structure. Obtaining highly crystalline or graphitic carbonmaterials can be very advantageous because of the unique propertiesexhibited by graphite. For example, graphitic materials can be thermallyand electrically conductive.

Recently, methods have been developed to make highly ordered graphiticstructures such as carbon nanotubes. One way to make graphiticnanostructures is to carbonize a carbon precursor (carbon gas or carbonresin) in the presence of a metal catalyst. The catalyst is typically asalt of iron, nickel, or cobalt that is mixed with carbon precursor andthen heated. During the carbonization process, the carbon nanostructuregrows from or around the catalytic metal to yield a well orderedstructure. The metal catalyst can be removed from the carbonnanomaterial by treating with strong acids. Amorphous carbon can beremoved using an oxidizing agent such as potassium permanganate.

BRIEF SUMMARY OF THE INVENTION

The present invention relates to methods for reducing the particle sizeof agglomerates of carbon nanospheres by dispersing the carbonnanospheres in an organic solvent. The carbon nanospheres aremulti-walled, hollow, graphitic structures with an average diameter in arange from about 10 nm to about 200 nm, more preferably about 20 nm toabout 100 nm. Spectral data shows that prior to being dispersed, thecarbon nanospheres are agglomerated into clusters that range in sizefrom 500 nm to 5 microns. In the method of the present invention, theclusters of nanospheres are reduced in size by dispersing the carbonnanospheres in an organic solvent using ultrasonication. The solventsthat can be used are organic molecules having one or more electron-richheteroatoms such as oxygen or nitrogen (e.g., N-methylpyrrolidone orpyridine). The combination of this type of organic solvent andultrasonication is able to break tip and disperse agglomerates of carbonnanospheres. Unexpectedly, agglomerates of carbon nanospheres with anaverage particle size of 500 nm to 5 microns can be dispersed using theinventive methods to yield nanospheres and/or agglomerates ofnanospheres with an average particle size of less than about 300 nm,more preferably less than about 200 nm, and most preferably less thanabout 150 nm as measured using dynamic light scattering.

The combination of an organic solvent having electron-rich heteroatomsand ultrasonication can yield a very stable dispersion of carbonnanospheres within the organic solvent. Carbon nanospheres dispersedusing the method of the invention can be stable in the organic solventfor hours, days, months, or even longer. Surprisingly, the particle sizedistribution can be very narrow. In contrast to just sonicating in wateror an aliphatic solvent, the combination of ultrasonicating the carbonnanospheres in a organic solvent having a heteroatom can yield a carbonnanomaterial with a surprisingly narrow particle size distribution asmeasured using dynamic light scattering. In one embodiment, at least 80%of the carbon nanomaterial has an average particle size of less than 500nm, more preferably less than 300 nm, and most preferably less than 200nm. More preferably at least 90% of the carbon nanomaterial has anaverage particle size within one or more of the foregoing particle sizeranges.

The small particle size, narrow particle size distribution, andstability of the suspended carbon nanospheres in the solvent isparticularly advantageous for using the dispersed carbon nanomaterialsin various applications including, but not limited to, fillers,pigments, supercapacitors, and high-performance electrodes.

Optionally the organic solvent can be combined with a surface modifyingagent. The surface modifying agent can be any organic molecule that issoluble in the organic solvent and has one or more functional groupsthat can bond with the carbon nanospheres. The surface modifying agentcan be a surfactant, an organic acid, a carbohydrate, an amino acid, andthe like. Examples of suitable functional groups include carboxyl,amine, sulfonate, and/or hydroxyl groups. Specific examples of compoundsthat can be used as a surface modifying agent include glucose, glycolicacid, glycine, ascorbic acid, sodium dodecyl benzene sulfonate,phosphotungstic acid, and trifluoroacetic acid. In one embodiment, thesurface modifying agent is a biocompatible organic molecule such as, butnot limited to, glucose, glycolic acid, glycine, or ascorbic acid.

In one embodiment, the organic solvent can be a biocompatible solvent.The use of a biocompatible solvent (and optionally a biocompatiblesurface modifying agent), in combination with a desired particle sizedistribution is particularly advantageous for using the carbonnanospheres in biomedical applications.

In one embodiment the carbon nanospheres include oxygen-containingsurface functional groups that provide a bonding site for the surfacemodifying agent. The oxygen-containing surface functional groups can beintroduced during purification of the carbon nanospheres or can beintroduced using a severe oxidizing agent. It has been found thatoxygen-containing functional groups can be highly beneficial fordispersing the carbon nanospheres according to the invention when theconcentration of surface oxygen is at least about 2 wt % surface oxygenas measured using XPS, more preferably at least about 5 wt %, even morepreferably at least about 10 wt %, and most preferably at least about 15wt %. The carbon nanospheres of the present invention also include anirregular surface. The irregular surface can be beneficial forintroducing surface functional groups and can facilitate dispersing ofthe carbon nanospheres in the organic solvent.

To disperse the carbon nanospheres, the carbon nanospheres are mixedwith the organic solvent and then ultrasonicated. The chemicaladsorption and/or bonding of the organic solvent during ultrasonicationbreaks up agglomerates of carbon nanospheres and disperses the carbonnanospheres and/or smaller agglomerates of carbon nanospheres into theorganic solvent. The ultrasonication can be carried out for a period ofabout 0.5 hr to about 6 hr, more preferably for about 1 hr to about 4hr.

The term “ultrasonication” is well known in the art and refers to aprocess in which ultrasonic sound waves are input into a vessel. In thiscase, the vessel will contain the organic solvent, carbon nanospheresand/or agglomorates, and optional components.

The carbon nanospheres dispersed using the methods of the invention havebeen found to retain the beneficial structure, shape, and graphiticnature of the undispersed carbon nanospheres. The dispersed carbonnanospheres are highly graphitic, which is advantageous for providingstrength, electrical conductivity, thermal conductivity, and otherdesired properties.

These and other advantages and features of the present invention willbecome more fully apparent from the following description and appendedclaims as set forth below.

BRIEF DESCRIPTION OF THE DRAWINGS

To further clarify the above and other advantages and features of thepresent invention, a more particular description of the invention willbe rendered by reference to specific embodiments thereof which areillustrated in the appended drawings. It is appreciated that thesedrawings depict only typical embodiments of the invention and aretherefore not to be considered limiting of its scope. The invention willbe described and explained with additional specificity and detailthrough the use of the accompanying drawings in which:

FIG. 1 is a dynamic light scattering spectrum of carbon nanospheresprior to being dispersed in an organic solvent according to theinvention;

FIG. 2A is a high resolution SEM image of carbon nanospheresagglomerated into a plurality of nanosphere clusters;

FIG. 2B is a high resolution SEM image showing a closer image ofindividual clusters of carbon nanospheres of FIG. 2A and showing onecluster that has been broken open to reveal the plurality of carbonnanospheres that make up the cluster;

FIG. 2C is a high resolution TEM image of the carbon nanomaterial ofFIG. 2A showing a plurality of carbon nanospheres agglomerated togetherand revealing the multi-walled and hollow nature of the carbonnanospheres that form the cluster;

FIG. 3 is a dynamic light scattering spectrum of carbon nanospheresdispersed according to the present invention;

FIG. 4A is an SEM image of the carbon nanospheres of FIG. 2A after beingdispersed in an organic solvent according to one embodiment of theinvention;

FIG. 4B is a TEM image of the carbon nanospheres of FIG. 4A; and

FIG. 5 is a comparative dynamic light scattering spectrum of carbonnanospheres ultrasonicated in plain water for 2 hours.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS I. Introduction andDefinitions

The present invention relates to carbon nanospheres dispersed in anorganic solvent using ultrasonication. The dispersion of the carbonnanospheres reduces the average particle size as measured using dynamiclight scattering. Using the methods of the invention, the averageparticle size is reduced from greater than about 500 nm to less thanabout 300 nm, more preferably less than about 200 nm. The dispersedcarbon nanospheres have unique properties due to their size anddispersion in the organic solvent.

For purposes of the present invention, the term average particle size ofthe carbon nanomaterial is determined using dynamic light scattering andcorresponds to a peak of the light scattering spectral data. Where morethan one significant peak is observed, the average diameter shall meanthe weighted average according to the % intensity for the two or morepeaks, unless otherwise indicated.

II. Components Used to Manufacture Dispersed Carbon Nanospheres

A. Carbon Nanomaterials Containing Carbon Nanospheres

The carbon nanospheres used in the method of the invention aremulti-walled, hollow, graphitic strictures with an average diameter in arange from about 10 nm to about 200 nm, preferably about 20 nm to about100 nm. The multiple walls form a closed structure with a hollow center.

Typically, the individual carbon nanospheres have an aspect ratio ofless than about 3:1 (i.e., width to height is less than 3:1), preferablyless than about 2:1, more preferably less than about 1.75:1, and mostpreferably less than about 1.5:1. In one embodiment, the carbonnanospheres have an irregular surface. The irregular surface has defectsthat cause the nanospheres to have a shape that is not perfectlyspherical. The graphitic defects are believed to contribute in part tothe dispersibility of the carbon nanospheres in the organic solvent. Thecarbon nanospheres are highly graphitic, which gives the carbonnanomaterial excellent electrical and thermal conductivity.

Typically, the thickness of the carbon nanosphere wall is between about1 nm and 20 nm. However, thicker and thinner walls can be made ifdesired. The thickness of the nanostructure wall is measured from theinside diameter of the wall to the outside diameter of the wall. In oneembodiment, the carbon nanostructures have walls of between about 2 andabout 100 graphite layers, preferably between about 5 and 50 graphitelayers, and more preferably between about 5 and 20 graphite layers. Thenumber of graphitic layers can be varied by varying the thickness of thecarbon nanostructure wall as discussed below in relation to methods formanufacturing carbon nanospheres. The advantage of making a thicker wallis greater structural integrity. The advantage of making a thinner wallis greater surface area and nanoporosity.

The spheroidal shape and multi-walled nature of the carbon nanospheresalso provides strength that makes the carbon nanospheres less likely tobe crushed or broken into undesired shapes or non-shaped graphite.Maintaining the shape of the carbon nanospheres can be important formaintaining performance characteristics over time. The multi-wallednature of the nanospheres also allows the surface to be functionalizedwhile maintaining the beneficial thermal and electrical conductivity viathe interior graphite layers. The hollow center gives the nanomaterial arelatively lower density and higher porosity. In one embodiment, thesurface area is in a range from about 100 m²/g to about 400 m²/g,preferably about 125 m²/g to about 300 m²/g, and more preferably about150 m²/g to about 250 m²/g.

The carbon nanomaterials are, prior to dispersion, typically provided asagglomerated particles of carbon nanospheres. While the individualcarbon nanospheres have a diameter of less than 500 nm, the carbonnanospheres tend to agglomerate to form clusters (i.e., particles ofagglomerated nanospheres) with average diameters greater than 500 nm.Spectral data shows that prior to being dispersed, the carbonnanospheres are agglomerated into clusters that range in size from 500nm to 5 microns. FIG. 1 is a graph showing the size distribution of acarbon nanomaterial used in one embodiment of the invention, prior tothe carbon nanomaterial being dispersed. As seen in FIG. 1, the averageparticle diameter is about 1.4 microns as measured using dynamic lightscattering.

FIGS. 2A and 2B are SEM images of a cluster of nanospheres. In FIGS. 2Aand 2C, the images reveal that, at least in some embodiments, the carbonnanospheres are clustered together to form a “grape-like” secondarystructure. FIG. 2B is a close-up of some of the clusters, with onecluster broken open thereby exposing a plurality of carbon nanospheres.The TEM image in FIG. 2C further shows that the clusters are made up ofa plurality of smaller nanospheres. The SEM and TEM images reveal thatthe nanostructures are hollow and generally spheroidal.

In one embodiment, the carbon nanospheres can be one of severalcomponents of a carbon nanomaterial. Higher percentages of carbonnanospheres are typically preferred such that the carbon nanomaterialcan benefit from the unique properties of the carbon nanospheres. In oneembodiment, the nanospheres are at least about 10 wt % of the carbonnanomaterial, preferably at least about 50 wt %, more preferably about75 wt %, even more preferably at least about 90 wt %, and mostpreferably at least about 98 wt %. The portion of the carbonnanomaterial that is not carbon nanospheres is preferably a graphiticmaterial such as graphite sheets or other graphitic nanostructures. Thecarbon nanomaterials can include non-graphitic amorphous carbon.However, it is typically advantageous to minimize the percentage ofnon-graphitic amorphous carbon (e.g., by removing it during purificationand/or by converting non-graphitic amorphous carbon to graphite duringadditional heat treatment steps).

The carbon nanospheres typically include oxygen-containing surfacefunctional groups that can bond or otherwise interact with the solvent.It has been found that oxygen-containing functional groups can be highlybeneficial for dispersing the carbon nanospheres according to theinvention when the concentration of surface oxygen is at least about 2wt % surface oxygen as measured using XPS, preferably at least about 5wt %, more preferably at least about 10 wt %, and most preferably atleast about 15 wt % of surface oxygen as measured using XPS.

The carbon nanospheres can be treated to introduce oxygen-containingfunctional groups on the surface. Examples of suitable oxidizing agentsinclude sulfuric acid, KMnO₄, H₂O₂, 5M or greater HNO₃, and aqua regia.The foregoing oxidizing agents tend to introduce less than about 9 wt %oxygen to the surface of the carbon nanospheres as measured using XPS.If desired, higher wt % oxygen-containing functional groups can beachieved using severe oxidizing agents. Introducing oxygen-containingfunctional groups can be beneficial to provide desired quantities oflocations where the organic solvent chemically interact with the carbonnanospheres. Examples of suitable severe oxidizing agents include (i)mixtures of nitric acid and sulfuric acid, (ii) solutions of hydrogenperoxide, and (iii) mixtures of sulfuric acid and hydrogen peroxide.Specific examples of suitable concentrations for severe oxidationinclude, but are not limited to, a mixture of sulfuric acid and nitricacid (70%) in a 3:1 v/v ratio; a solution of 30% hydrogen peroxide; or amixture of sulfuric acid (98%) and hydrogen peroxide (30%) in a 4:1 v/vratio.

B. Surface Modifying Agents

Optionally, a surface modifying agent can be combined with the organicsolvent to facilitate dispersion and/or stability. The surface modifyingagent used in the invention is an organic molecule that is soluble inthe organic solvent and has one or more functional groups that can bondwith the carbon nanospheres. The surface modifying agent can be asurfactant, an organic acid, a carbohydrate, an amino acid, and thelike. Examples of suitable functional groups for bonding with thesurface of the carbon nanospheres include carboxyl, amine, sulfonate,and/or hydroxyl groups. In some embodiments, the functional groups areselected to bond with oxygen-containing functional groups on the surfaceof the carbon nanospheres (e.g., hydroxyl or carboxyl groups). Specificexamples of compounds that can be used as a surface modifying agentinclude glucose, glycolic acid, glycine, ascorbic acid, sodium dodecylbenzene sulfonate, phosphotungstic acid, trifluoroacetic acid, and thelike.

C. Organic Solvents

The organic solvent is a hydrocarbon that includes at least oneheteroatom. In a preferred embodiment, the at least one heteroatom is anelectron-rich atom such as an oxygen or nitrogen atom. The organicsolvent can be straight chained, but is preferably a cyclic compound. Inone embodiment, the heteroatom is a constituent of the ring of thecyclic compound. Examples of suitable organic solvents includeN-methylpyrrolidone (NMP); pyridine; imidazoles derivatives, including1-(3 aminopropyl)imidazoles, 1-Diethoxy methyl imidazoles,1-2-(hydroxyethyl)imidazoles, 4(1H-imidazole-1-yl)aniline, 4(imidazole1-yl)phenol; barbituric acid; 1-methyl 2-pyrrolidinone hydrazonehydrochloride; quinoxaline and its derivatives; pyridine derivatives;1-ethyl-4-piperidone; 1-ethylpiperazine; ethyl 2-picolinate.

Surprisingly, it has been found that cyclic compounds containingnitrogen and/or oxygen (e.g., NMP), work particularly well fordispersing carbon nanospheres using ultrasonication. In one embodiment,the organic solvent is a biocompatible solvent such as, but not limitedto, NMP or pyridine such that the dispersion can be used for biologicalapplications.

III. Methods for Dispersing Carbon Nanospheres

In the method of the present invention, the clusters of nanospheres arereduced in size by dispersing the carbon nanospheres in the organicsolvent using ultrasonication and optionally a surface modifying agent.

The method generally includes selecting an organic solvent with at leastone heteroatom that can bond to or interact with the surface of thecarbon nanospheres. To disperse the carbon nanospheres, a mixture of theorganic solvent and the carbon nanospheres is formed. Optionally thismixture can also include a surface modifying agent to facilitatedispersion and/or the stability of the dispersed carbon nanomaterial.The carbon nanomaterial containing the carbon nanospheres is typicallyincluded in the mixture in a concentration in a range from about 0.1 wt% to about 20 wt %, more preferably from about 1 wt % to about 10 wt %.If the surface modifying agent is included, the concentration istypically in a range from about 0.5 wt % to about 20 wt %, morepreferably about 5 wt % to about 10 wt %.

The carbon nanospheres are dispersed into the solvent usingultrasonication. Ultrasonication can be carried out using any suitabletechnique, such as ultrasonic bath, to vibrate the carbon nanospheres atultrasonic frequencies. An example of an ultrasonication device suitablefor use in dispersing carbon nanospheres is CREST ULTRASONICS TRU-SWEEP™(68 kHz frequencies and 500 watt).

Ultrasonication is typically carried out for at least 30 min, preferablyat least about 1 hour, and more preferably at least about 2 hours.Examples of suitable ranges of time for carrying out ultrasonication ofthe mixture include about 30 minutes to about 6 hours and preferablyabout 1 hour to about 4 hours. The ultrasonication step can be carriedout at room temperature or other suitable temperatures.

The combination of the organic solvent, ultrasonication, and optionallya surface modifying agent is able to break up and disperse agglomeratesof carbon nanospheres. Unexpectedly, agglomerates of carbon nanosphereswith an average particle size of 500 mm to 5 microns can be dispersedusing the inventive methods to yield nanospheres and/or agglomerates ofnanospheres with an average particle size of less than about 300 mm,more preferably less than about 200 mm, and most preferably less thanabout 150 nm as measured using dynamic light scattering.

Dynamic light scattering data of the dispersed carbon nanospheres of theinvention illustrate the significant reduction in average particle sizeachieved using the method of the present invention. FIG. 3 is a graphshowing the dynamic light scattering of a carbon nanomaterial dispersedusing the method of the present invention, which is described in detailbelow in Example 2. As shown in FIG. 3, in one embodiment, the method ofthe invention yielded dispersed carbon nanospheres with an averageparticle size of 147 nm. FIGS. 4A and 4B are SEM and TEM images,respectively, of carbon nanospheres after they have been dispersedaccording to the present invention. FIGS. 4A and 4B can be compared toFIGS. 2B and 2C, which show the carbon nanomaterials of FIGS. 4A and 4Bprior to being dispersed according to the invention. This comparison ofthe Figures reveals the significant improvement in dispersion achievedusing the methods of the present invention.

In addition to the improved dispersion, the dispersed carbon nanospheresalso tend to have a relatively narrow distribution of particle sizes. Inone embodiment, the width of the particle size distribution is in arange from about 10 nm to about 300 nm.

Carbon nanospheres dispersed according to the methods of the presentinvention advantageously retain their beneficial properties such asmulti-walled, hollow, closed structure, graphitic nature, and originalsize and shape of the primary structures. The carbon nanospheres shownin the TEM image of FIG. 4B reveal highly dispersed carbon nanosphereswith similar primary structure as the carbon nanospheres in the clustersof FIG. 2C prior to dispersion.

The carbon nanospheres dispersed according to the present invention havebeen found to be surprisingly stable in the organic solvent. Carbonnanospheres manufactured according to the present invention have beenobserved to be stable for months at room temperature. In one embodimentof the invention, the carbon nanospheres are stable for at least aboutone hour, more preferably at least about one day, and most preferably atleast about one month.

The dispersed carbon nanospheres are particularly advantageous formaking composites. Because the carbon nanospheres are readilydispersible, the carbon nanospheres can be mixed with other materials toform composites. The composites of the invention can benefit from thenarrow particle size distribution and unique properties of the carbonnanospheres of the invention, including strength, electrical and thermalconductivity, porosity, surface area, etc.

IV. Manufacturing Carbon Nanospheres

The carbon nanospheres used in the methods of the present invention canbe manufactured using any technique that provides carbon nanosphereshaving the desired properties described above. In one embodiment, themethod for manufacturing carbon nanospheres generally includes (1)forming a precursor mixture that includes a carbon precursor and aplurality of catalytic templating particles, (2) carbonizing theprecursor mixture to form an intermediate carbon material includingcarbon nanostructures, amorphous carbon, and catalytic metal, and (3)purifying the intermediate carbon material by removing at least aportion of the amorphous carbon and optionally at least a portion of thecatalytic metal. The following components can be used to carry out theabove mentioned steps for manufacturing carbon nanospheres according tothe present invention.

A. Components Used to Make Carbon Nanospheres

(1) Carbon Precursor

Any type of carbon material can be used as the carbon precursor of thepresent invention so long as it can disperse the templating particlesand carbonize around the templating particles upon heat treating.Suitable compounds include single and multi-ring aromatic compounds suchas benzene and naphthalene derivatives that have polymerizablefunctional groups. Also included are ring compounds that can form singleand multi-ring aromatic compounds upon heating. Functional groups thatcan participate in polymerization include COOH, C═O, OH, C═C, SO₃, NH₂,SOH, N═C═O, and the like.

The carbon precursor can be a single type of molecule (e.g., a compoundthat can polymerize with itself), or the carbon precursor can be acombination of two or more different compounds that co-polymerizetogether. For example, in one embodiment, the carbon precursor can be aresorcinol-formaldehyde gel. In this two compound embodiment, theformaldehyde acts as a cross-linking agent between resorcinol moleculesby polymerizing with the hydroxyl groups of the resorcinol molecules.

Other examples of suitable carbon precursors include resorcinol, phenolresin, melamine-formaldehyde gel, poly(furfuryl alcohol),poly(acrylonitrile), sucrose, petroleum pitch, and the like. Otherpolymerizable benzenes, quinones, and similar compounds can also be usedas carbon precursors and are known to those skilled in the art.

In one embodiment, the carbon precursor is a hydrothermallypolymerizable organic compound. Suitable organic compounds of this typeinclude citric acid, acrylic acid, benzoic acid, acrylic ester,butadiene, styrene, cinnamic acid, and the like.

(2) Catalytic Templating Nanoparticles

The catalytic templating nanoparticles are used as a template for makingthe nanostructures. When mixed with the carbon precursor, the templatingnanoparticles provide a nucleation site where carbonization and/orpolymerization can begin or be enhanced. Because the templatingnanoparticles are made from catalytic atoms, the templating particlescan advantageously serve as both a nucleating site and as a catalyst forcarbonization and/or polymerization.

The catalytic templating particles can be formed in more than one way.As described below, in one embodiment, the templating particles areformed from metal salts that agglomerate to form particles. Optionally,the catalyst atoms can be complexed with a dispersing agent to controlformation of the particles. Templating nanoparticles formed using adispersing agent tend to be more uniform in size and shape thantemplating particles formed without a dispersing agent.

(i) Catalyst Atoms

The catalyst atom used to form the templating nanoparticles can be anymaterial that can cause or promote carbonization and/or polymerizationof the carbon precursor. In a preferred embodiment, the catalyst is atransition metal catalyst including but not limited to iron, cobalt, ornickel. These transition metal catalysts are particularly useful forcatalyzing many of the polymerization and/or carbonization reactionsinvolving the carbon precursors described above.

(ii) Dispersing Agents

Optionally, a dispersing agent can be complexed with the catalyst atomsto control formation of the templating nanoparticles. The dispersingagent is selected to promote the formation of nanocatalyst particlesthat have a desired stability, size and/or uniformity. Dispersing agentswithin the scope of the invention include a variety of small organicmolecules, polymers and oligomers. The dispersing agent is able tointeract and bond with catalyst atoms dissolved or dispersed within anappropriate solvent or carrier through various mechanisms, includingionic bonding, covalent bonding, Van der Waals interaction/bonding, lonepair electron bonding, or hydrogen bonding.

To provide the bonding between the dispersing agent and the catalystatoms, the dispersing agent includes one or more appropriate functionalgroups. Preferred dispersing agents include functional groups which haveeither a charge or one or more lone pairs of electrons that can be usedto complex a metal catalyst atom, or which can form other types ofbonding such as hydrogen bonding. These functional groups allow thedispersing agent to have a strong binding interaction with the catalystatoms.

The dispersing agent may be a natural or synthetic compound. In the casewhere the catalyst atoms are metal and the dispersing agent is anorganic compound, the catalyst complex so formed may be anorganometallic complex.

In one embodiment, the functional groups of the dispersing agentcomprise one or more members selected from the group of a hydroxyl, acarboxyl, a carbonyl, an amine, an amide, a nitrile, a nitrogen with afree lone pair of electrons, an amino acid, a thiol, a sulfonic acid, asulfonyl halide, or an acyl halide. The dispersing agent can bemonofunctional, bifunctional, or polyfunctional.

Examples of suitable monofunctional dispersing agents include alcoholssuch as ethanol and propanol and carboxylic acids such as formic acidand acetic acid. Useful bifunctional dispersing agents include diacidssuch as oxalic acid, malic acid, malonic acid, maleic acid, succinicacid, and the like; dialcohols such as ethylene glycol, propyleneglycol, 1,3-propanediol, and the like; hydroxy acids such as glycolicacid, lactic acid, and the like. Useful polyfunctional dispersing agentsinclude sugars such as glucose, polyfunctional carboxylic acids such ascitric acid, pectins, cellulose, and the like. Other useful dispersingagents include ethanolamine, mercaptoethanol, 2-mercaptoacetate, aminoacids, such as glycine, and sulfonic acids, such as sulfobenzyl alcohol,sulfobenzoic acid, sulfobenzyl thiol, and sulfobenzyl amine. Thedispersing agent may even include an inorganic component (e.g.,silicon-based).

Suitable polymers and oligomers within the scope of the inventioninclude, but are not limited to, polyacrylates, polyvinylbenzoates,polyvinyl sulfate, polyvinyl sulfonates including sulfonated styrene,polybisphenol carbonates, polybenzimidizoles, polypyridine, sulfonatedpolyethylene terephthalate. Other suitable polymers include polyvinylalcohol, polyethylene glycol, polypropylene glycol, and the like.

In addition to the characteristics of the dispersing agent, it can alsobe advantageous to control the molar ratio of dispersing agent to thecatalyst atoms in a catalyst suspension. A more useful measurement isthe molar ratio between dispersing agent functional groups and catalystatoms. For example, in the case of a divalent metal ion two molarequivalents of a monovalent functional group would be necessary toprovide the theoretical stoichiometric ratio. In a preferred embodiment,the molar ratio of dispersing agent functional groups to catalyst atomsis preferably in a range of about 0.01:1 to about 100:1, more preferablyin a range of about 0.05:1 to about 50:1, and most preferably in a rangeof about 0.1:1 to 20:1.

The dispersing agents of the present invention allow for the formationof very small and uniform nanoparticles. In general, the nanocatalystparticles formed in the presence of the dispersing agent are less than 1micron in size. Preferably the nanoparticles are less than about 100 mm,more preferably less than about 50 nm and most preferably less thanabout 20 nm.

During pyrolysis of the carbon precursor, the dispersing agent caninhibit agglomeration and deactivation of the catalyst particles. Thisability to inhibit deactivation can increase the temperature at whichthe nanocatalysts can perform and/or increase the useful life of thenanocatalyst in the extreme conditions of pyrolysis. Even if includingthe dispersing agent only preserves catalytic activity for a fewadditional milliseconds, or even microseconds, the increased duration ofthe nanocatalyst can be very beneficial at high temperatures, given thedynamics of carbonization.

(iii) Solvents and Other Additives

A solvent can optionally be used to prepare the catalyst atoms formixing with the dispersing agent and/or the carbon precursor. The liquidmedium in which the catalytic templating nanoparticles are prepared maycontain various solvents, including water and organic solvents. Solventsparticipate in particle formation by providing a liquid medium for theinteraction of catalyst atoms and dispersing agent. In some cases, thesolvent may act as a secondary dispersing agent in combination with aprimary dispersing agent that is not acting as a solvent. In oneembodiment, the solvent also allows the nanoparticles to form asuspension. Suitable solvents include water, methanol, ethanol,n-propanol, isopropyl alcohol, acetonitrile, acetone, tetrahydrofuran,ethylene glycol, dimethylformamide, dimethylsulfoxide, methylenechloride, and the like, including mixtures thereof.

The catalyst composition can also include additives to assist in theformation of the nanocatalyst particles. For example, mineral acids andbasic compounds can be added, preferably in small quantities (e.g., lessthan 5 wt %). Examples of mineral acids that can be used includehydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, and thelike. Examples of basic compounds include sodium hydroxide, potassiumhydroxide, calcium hydroxide, ammonium hydroxide, and similar compounds.

It is also possible to add solid materials to assist in nanoparticleformation. For example, ion exchange resins may be added to the solutionduring catalyst formation. Ion exchange resins can be substituted forthe acids or bases mentioned above. Solid materials can be easyseparated from the final iron catalyst solution or suspension usingsimple techniques such as centrifugation and filtration.

(3) Reagents for Purifying Intermediate Carbon Materials

Various reagents can be used to remove amorphous carbon and/or thecatalytic metals from the carbon nanostructures, thereby purifying theintermediate material. The purification can be carried out using anyreagent or combination of reagents capable of selectively removingamorphous carbon (or optionally catalytic metal) while leaving graphiticmaterial.

Reagents for removing amorphous carbon include oxidizing acids,oxidizing agents, and mixtures of these. An example of a mixturesuitable for removing amorphous carbon includes sulfuric acid, KMnO₄,H₂O₂, 5M or greater HNO₃, and aqua regia.

The catalytic metal can be removed using any reagent that canselectively dissolve the particular metal used as catalyst withoutsignificantly destroying the carbon nanostructures, which are graphitic.Nitric acid is an example of a reagent suitable for dissolving many basetransition metals such as, but not limited to, iron, cobalt, and nickel.Other examples of suitable reagents include hydrogen fluoride,hydrochloric acid, and sodium hydroxide. If desired, additional heattreatment steps can be carried out on the intermediate carbon to convertall or some of the remaining amorphous carbon to graphite. Thesubsequent heat treatment can be carried out at a temperature aboveabout 250° C., more preferably above about 500° C.

B. Process for Making Carbon Nanospheres

The carbon nanostructures of the present invention can be manufacturedusing all or a portion of the following steps: (i) forming a precursormixture that includes a carbon precursor and a plurality of templatingnanoparticles, (ii) allowing or causing the carbon precursor topolymerize around the catalytic templating nanoparticles, (iii)carbonizing the precursor mixture to form an intermediate carbonmaterial that includes a plurality of nanostructures (e.g., carbonnanospheres), amorphous carbon, and catalytic metal, and (iv) purifyingthe intermediate carbon material by removing at least a portion of theamorphous carbon and optionally a portion of the catalytic metal. Thepurification step can also include removing oxygen containing functionalgroups generated during the removal of amorphous carbon or addingadditional oxygen-containing functional groups to impart greaterhydrophilicity to the carbon nanospheres.

(1) Forming a Precursor Mixture

The precursor mixture is formed by selecting a carbon precursor anddispersing a plurality of catalytic templating nanoparticles in thecarbon precursor.

The catalytic templating nanoparticles, which are dispersed in thecarbon precursor, can be provided in several different ways. Thetemplating nanoparticles can be formed in the carbon precursor (i.e.,in-situ) or formed in a separate reaction mixture and then mixed withthe carbon precursor. In some cases, particle formation may partiallyoccur in a separate reaction and then be completed as the templatingparticles are mixed and/or heated in the carbon precursor (e.g., at theonset of a precursor polymerization step). The templating nanoparticlescan also be formed using a dispersing agent that controls one or moreaspects of particle formation or the templating nanoparticles can bemade from metal salts.

In one embodiment, the templating nanoparticles are formed in the carbonprecursor from a metal salt. In this embodiment, the templatingnanoparticles are formed by selecting one or more catalyst metal saltsthat can be mixed with the carbon precursor. The metal salts are mixedwith the carbon precursor and then allowed or caused to formnanoparticles in-situ.

In a more preferred embodiment, the templating particles are formed(in-situ or ex-situ) using a dispersing agent to control particleformation. In this embodiment, one or more types of catalyst atoms andone or more types of dispersing agents are selected. Next, the catalystatoms (e.g., in the form of a ground state metal or metal salt) anddispersing agent (e.g., in the form of a carboxylic acid or its salt)are reacted or combined together to form catalyst complexes. Thecatalyst complexes are generally formed by first dissolving the catalystatoms and dispersing agent in an appropriate solvent and then allowingthe catalyst atoms to bond with the dispersing agent molecules. Thevarious components may be combined or mixed in any sequence orcombination. In addition, a subset of the components can be premixedprior to addition of other components, or all components may besimultaneously combined.

In an embodiment of the invention, the components for the templatingnanoparticles are allowed or caused to form nanoparticles by mixing thecomponents for a period of about 1 hour to about 14 days. This mixing istypically conducted at temperatures ranging from about 0° C. to about200° C. In one embodiment, the temperature does not exceed 100° C.Particle formation can also be induced using a reagent. For example, insome cases formation of particles or intermediate particles can becaused by bubbling hydrogen through the solution of catalyst complexes.

The templating nanoparticles of the present invention are capable ofcatalyzing polymerization and/or carbonization of the carbon precursor.The concentration of catalytic templating nanoparticles in the carbonprecursor is typically selected to maximize the number of carbonnanostructures formed. The amount of catalytic templating particles canvary depending on the type of carbon precursor being used. In an exampleembodiment the molar ratio of carbon precursor to catalyst atoms isabout 0.1:1 to about 100:1, more preferably about 1:1 to about 30:1.

(2) Polymerizing the Precursor Mixture

The precursor mixture is typically allowed to cure for sufficient timesuch that a plurality of intermediate carbon nanostructures are formedaround the templating nanoparticles. Because the templatingnanoparticles are catalytically active, the templating nanoparticles canpreferentially accelerate and/or initiate polymerization of the carbonprecursor near the surface of the templating particles.

The time needed to form intermediate nanostructures depends on thetemperature, the type and concentration of the catalyst material, the pHof the solution, and the type of carbon precursor being used. Duringpolymerization, the intermediate carbon nanostructures can be individualorganic structures or an association of nanostructures that break apartduring carbonization and/or removal of amorphous carbon.

Ammonia added to adjust the pH can also effect polymerization byincreasing the rate of polymerization and by increasing the amount ofcross linking that occurs between precursor molecules.

For hydrothermally polymerizable carbon precursors, polymerizationtypically occurs at elevated temperatures. In a preferred embodiment,the carbon precursor is heated to a temperature of about 0° C. to about200° C., and more preferably between about 25° C. to about 120° C.

An example of a suitable condition for polymerization ofresorcinol-formaldehyde gel (e.g., with iron particles and a solution pHof 1-14) is a solution temperature between about 0° C. and about 90° C.and a cure time of less than 1 hour to about 72 hours. Those skilled inthe art can readily determine the conditions necessary to cure othercarbon precursors under the same or different parameters.

In one embodiment the polymerization is not allowed to continue tocompletion. Terminating the curing process before the entire solution ispolymerized can help to form a plurality of intermediate nanostructuresthat will result in individual nanostructures, rather than a single massof carbonized material. However, the present invention includesembodiments where the carbon precursor forms a plurality of intermediatecarbon nanostructures that are linked or partially linked to oneanother. In this embodiment, individual nanostructures are formed duringcarbonization and/or during the removal of amorphous carbon.

Forming intermediate carbon nanostructures from the dispersion oftemplating nanoparticles causes formation of a plurality of intermediatecarbon nanostructures having unique shapes and sizes. Ultimately, theproperties of the nanostructure can depend at least in part on the shapeand size of the intermediate carbon nanostructure. Because of the uniqueshapes and sizes of the intermediate carbon nanostructures, the finalnanostructures can have beneficial properties such as high surface areaand high porosity, among others.

(3) Carbonizing the Precursor Mixture

The precursor mixture is carbonized by heating to form an intermediatecarbon material that includes a plurality of carbon nanostructures,amorphous carbon, and catalyst metal. The precursor mixture can becarbonized by heating the mixture to a temperature between about 500° C.and about 2500° C. During the heating process, atoms such as oxygen andnitrogen are volatilized or otherwise removed from the intermediatenanostructures (or the carbon around the templating nanoparticles) andthe carbon atoms are rearranged or coalesced to form a carbon-basedstructure.

The carbonizing step typically produces a graphite based nanostructure.The graphite based nanostructure has carbon atoms arranged in structuredsheets of sp² hybridized carbon atoms. The graphitic layers can provideunique and beneficial properties, such as electrical conduction andstructural strength and/or rigidity.

(4) Purifying the Intermediate Carbon Material

The intermediate carbon material is purified by removing at least aportion of non-graphitic amorphous carbon. This purification stepincreases the weight percent of carbon nanostructures in theintermediate carbon material.

The amorphous carbon is typically removed by oxidizing the carbon. Theoxidizing agents used to remove the amorphous carbon are selective tooxidation of the bonds found in non-graphitic amorphous carbon but areless reactive to the pi bonds of the graphitic carbon nanostructures.The amorphous carbon can be removed by applying the oxidative agents ormixtures in one or more successive purification steps.

Optionally substantially all or a portion of the catalytic metals can beremoved. Whether the catalytic metal is removed and the purity to whichthe catalytic metal is removed will depend on the desired amount ofmetal in the final product.

Typically, the templating nanoparticles are removed using acids or basessuch as nitric acid, hydrogen fluoride, or sodium hydroxide. The methodof removing the templating nanoparticles or amorphous carbon depends onthe type of templating nanoparticle or catalyst atoms in the composite.Catalyst atoms or particles (e.g., iron particles or atoms) cantypically be removed by refluxing the composite nanostructures in 5.0 Mnitric acid solution for about 3-6 hours.

Any removal process can be used to remove the templating nanoparticlesand/or amorphous carbon so long as the removal process does notcompletely destroy the carbon nanostructures. In some cases it may evenbe beneficial to at least partially remove some of the carbonaceousmaterial from the intermediate nanostructure during the purificationprocess.

During the purification process, the oxidizing agents and acids have atendency to introduce hydronium groups and oxygenated groups such as,but not limited to, carboxylates, carbonyls, and/or ether groups to thesurface of the carbonaceous materials. The oxidizing agents andconditions used to merely remove amorphous carbon typically introduceless than 9 wt % oxygen to the surface of the carbon nanostructures.

Optionally, the purification process can also include additional heattreatment steps at temperatures and conditions that can convert residualamorphous carbon to graphite. In this optional step, residual carbon ismore easily converted to a graphitic material since a substantialportion of the amorphous carbon has been removed and there is betterheat transfer to the portion that remains. If desired, oxygen-containingfunctional groups can be introduced to the surface of the carbonnanospheres by treating the intermediate carbon nanomaterial with asevere oxidizing agent. Generally, the duration of the oxidativetreatment will depend on the amount of amorphous carbon in theintermediate material (i.e., whether a prior purification step has beenperformed and if so, how much residual amorphous carbon remains), thestrength of the oxidizing agent, and the desired amount of functionalgroups to be introduced. Typically, the rate of functionalizationincreases with decreasing residual amorphous carbon and increases withincreasing oxidizing potential of the oxidizing agent. In oneembodiment, the oxidative treatment is carried out for a period of timein a range from about 2 hours to about 48 hours. To facilitateoxidation, the oxidative treatment can be carried out using sonication.

Carbon nanomaterials manufactured using the foregoing methods can beparticularly advantageous for use in the present invention due to theircontrolled size and shape. However, those skilled in the art willrecognize that the present invention can be carried out using carbonnanospheres manufactured using different methods than the foregoing.

V. Examples

The following examples provide formulas for making dispersed carbonnanomaterials containing carbon nanospheres according to the presentinvention.

Example 1

Example 1 describes the preparation of an intermediate carbonnanomaterial having carbon nanospheres that are agglomerated intoclusters with an average particle size greater than 1 micron as measuredusing dynamic light scattering.

(a) Preparation of Iron Solution (0.1 M)

A 0.1 M iron solution was prepared by using 84 g iron powder, 289 g ofcitric acid, and 15 L of water. The iron-containing mixture was mixed ina closed bottle on a shaker table for 3 days, with brief interruptionsonce or twice daily to purge the vapor space of the bottle with air gasbefore resuming mixing.

(b) Preparation of Precursor Mixture

916.6 g of resorcinol and 1350 g of formaldehyde (37% in water) wereplaced in a round bottom flask. The solution was stirred untilresorcinol was fully dissolved. 15 L of the iron solution from step (a)was slowly added with stirring, and then 1025 ml of Ammonium hydroxide(28-30% in water) was added drop-wise with vigorous stirring, the pH ofthe resulted suspension was 10.26. The slurry was cured at 80˜90° C.(water bath) for 10 hours. The solid carbon precursor mixture was thecollected using filtration and dried in an oven overnight.

(c) Carbonization

The polymerized precursor mixture was placed in a crucible with a coverand transferred to a furnace. The carbonization process was carried outunder ample nitrogen flow using the following temperature program: roomtemperature→1050° C. at a rate of 20° C./min→hold for 5 hrs at 1050°C.→room temperature. The carbonization step yielded an intermediatecarbon material having carbon nanostructures, amorphous carbon, andiron.

(d) Purification to Remove Amorphous Carbon and Iron

The purification of the carbonized carbon product (i.e., theintermediate carbon material) was performed as follows: refluxcarbonized product in 5M HNO₃ for ˜12 hrs→rinse with de-ionized(DI)-H₂O→treat with a mixture of KMnO₄+H₂SO₄+H₂O at a mole ratio of1:0.01:0.003 (keep at ˜90° C. for ˜12 hrs)→rinse with DI-H₂O→treat with4M HCl (keep at ˜90° C. for ˜12 hrs)→rinse with Di-H₂O→collect theproduct and dry in the oven at ˜100° C. for two days.

Example 2

Example 2 describes a method for preparing dispersed carbon nanospheresusing N-methylpyrrolidone (NMP) as the organic solvent andultrasonication.

100 ml of NMP was added to 3.0 g of carbon nanomaterial (greater than98% carbon nanospheres) in a glass container. The solution was thenmixed using ultrasound treatment for 2 hours. Ultrasonication to effectdispersion of nanospheres was performed using CREST ULTRASONICSTRU-SWEEP™ (68 kHz frequencies and 500 watt). The solution turned blackindicating the dispersion of the carbon nanospheres in the NMP. The 2 wt% dispersed carbon nanospheres continued to remain stably dispersed inthe NMP after three months. FIGS. 4A and 4B, are SEM and TEM images,respectively of the carbon nanospheres manufactured according to Example2. As discussed above, The SEM and TEM images show a dramaticimprovement in dispersion as compared to the undispersed carbonnanomaterial, which are shown in FIGS. 2A-2C.

FIG. 3 provides a graph of the dynamic light scattering of the dispersedcarbon nanospheres of Example 2. The light scattering data was collectedusing a MALVERN ZetaSizer (Nano Series). The sample was assayed using aquartz cuvette with an acquisition time of 360 s. As shown in the graph,the dispersed carbon nanospheres of Example 2 had an average particlesize of 125 nm. In contrast, the carbon nanospheres prior to dispersionhad an average particle size of 1.4 microns as shown in FIG. 1.

FIG. 5 shows the carbon nanospheres sonicated in water only.Surprisingly, the particle size distribution after sonication for 2hours in water only shows a peak at 5 microns and another peak at 254microns. This result is surprising because the results withoutsonication did not show a peak at 5 microns. Thus, it appears that insome cases, such as with pure water, sonication may result in bothparticle size reduction and agglomeration. In contrast, sonication withthe organic solvent according, to the invention produces significantlysmaller particle sizes and none of the larger agglomerates at 5 microns.

Example 3

Example 3 describes a method for preparing dispersed carbon nanospheresusing pyridine as a solvent.

100 ml of pyridine was added to 3.0 g of carbon nanomaterial (greaterthan 98% carbon nanospheres). The solution was then mixed usingultrasound treatment for 2 hours. Ultrasonication to effect dispersionof nanospheres was performed using CREST ULTRASONICS TRU-SWEEP™ (68 kHzfrequencies and 500 watt). The solution turned black indicating thedispersion of the carbon nanospheres in the pyridine. The averageparticle size as measured using dynamic light scattering was 138 nm. The1.7 wt % dispersed carbon nanospheres continued to remain stablydispersed in the pyridine after three months.

The present invention may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. The describedembodiments are to be considered in all respects only as illustrativeand not restrictive. The scope of the invention is, therefore, indicatedby the appended claims rather than by the foregoing description. Allchanges which come within the meaning and range of equivalency of theclaims are to be embraced within their scope.

1. A method for manufacturing a carbon nanomaterial dispersion,comprising; (i) providing a carbon nanomaterial comprising a pluralityof multi-walled, graphitic carbon nanospheres having an aspect ratio ofless than about 3:1 and optionally an irregular surface with surfacedefects, wherein the plurality of carbon nanospheres are at leastpartially agglomerated into a plurality of clusters of carbonnanospheres wherein the carbon nanospheres are manufactured by: forminga precursor mixture comprising a carbon precursor and a plurality oftemplating nanoparticles and polymerizing the carbon precursor, thetemplating nanoparticles comprising a catalytic metal; carbonizing theprecursor mixture to form an intermediate carbon material comprising aplurality of carbon nanostructures, amorphous carbon, and optionallyremaining catalytic metal; and purifying the intermediate carbonmaterial by removing at least a portion of the amorphous carbon andoptionally a portion of any remaining catalytic metal, thereby yieldinga carbon nanomaterial comprising a plurality of carbon nanostructures;(ii) providing an organic solvent comprised of a plurality of organicmolecules that each include at least one heteroatom; and (iii) mixingthe carbon nanomaterial with the solvent to form a mixture andultrasonicating the mixture to at least partially disrupt theagglomeration of the carbon nanospheres to yield carbon nanospheressuspended in the organic solvent.
 2. A method as in claim 1, wherein thecarbon nanomaterial in step (i) has an average particle size greaterthan about 500 nm as measured using dynamic light scattering.
 3. Amethod as in claim 1, wherein the carbon nanomaterial in step (iii) hasan average particle size of less than about 500 nm as measured usingdynamic light scattering.
 4. A method as in claim 1, wherein the carbonnanomaterial in step (iii) has an average particle size of less thanabout 300 nm as measured using dynamic light scattering.
 5. A method asin claim 1, wherein the carbon nanomaterial in step (iii) has an averageparticle size of less than about 200 nm as measured using dynamic lightscattering.
 6. A method as in claim 1, wherein the organic solventcomprises at least one of methylpyrrolidone (NMP), pyridine, 1-(3aminopropyl)imidazoles, 1-diethoxy methyl imidazoles,1-2(hydroxyethyl)imidazoles, 4(1H-imidazole-1-yl)aniline, 4(imidazole1-yl)phenol, barbituric acid, 1-methyl 2-pyrrolidinone hydrazonehydrochloride, quinoxaline, 1-ethyl-4-piperidone, 1-ethylpiperazine, orethyl 2-picolinate.
 7. A method as in claim 1, wherein the at least oneheteroatom is an oxygen atom, a nitrogen atom, or both.
 8. A method asin claim 1, wherein the organic solvent comprises a heterocycliccompound.
 9. A method as in claim 1, wherein the surface of the carbonnanomaterial has at least about 2 wt % oxygen as measured using X-rayphotoelectron spectroscopy (XPS).
 10. A method as in claim 1, whereinthe surface of the carbon nanomaterial has at least about 4 wt % oxygenas measured using X-ray photoelectron spectroscopy.
 11. A method as inclaim 1, wherein the surface of the carbon nanomaterial has at leastabout 8 wt % oxygen as measured using X-ray photoelectron spectroscopy.12. A method as in claim 1, wherein the carbon nanospheres areultrasonicated for at least about 30 minutes.
 13. A method as in claim1, in which the templating nanoparticles are prepared by, (a) reacting aplurality of precursor catalyst atoms with a plurality of organicdispersing agent molecules to form complexed catalyst atoms; and (b)allowing or causing the complexed catalyst atoms to form the templatingnanoparticles.
 14. A method for manufacturing a carbon nanomaterialdispersion, comprising; (i) providing an agglomerated carbonnanomaterial comprising a plurality of multi-walled, graphitic carbonnanospheres, the carbon nanospheres having an aspect ratio of less thanabout 3:1, an average diameter in a range from about 10 nm to about 200nm, and an irregular surface; (ii) providing an organic solventcomprised of a heterocyclic compound; and (iii) mixing the carbonnanomaterial with the organic solvent to form a mixture andultrasonicating the mixture to cause at least a portion of the organicmolecules to bond to the carbon nanospheres and suspend the carbonnanospheres in the organic solvent.
 15. A method as in claim 14, whereinthe carbon nanomaterial provided in step (i) has an average particlesize in a range from about 500 nm to about 5 microns as measured usingdynamic light scattering, and wherein the carbon nanomaterial in step(iii) has an average particle size less than about 300 nm as measuredusing dynamic light scattering.
 16. A method as in claim 14, wherein thecarbon nanomaterial provided in step (i) has an average particle size ina range from about 500 nm to about 5 microns as measured using dynamiclight scattering, and wherein the carbon nanomaterial in step (iii) hasan average particle size less than about 200 nm as measured usingdynamic light scattering.
 17. A method as in claim 14, wherein theorganic solvent comprises at least one of methylpyrrolidone (NMP),pyridine, 1-(3 aminopropyl)imidazoles, 1-diethoxy methyl imidazoles,1-2(hydroxyethyl)imidazoles, 4(1H-imidazole-1-yl)aniline, 4(imidazole1-yl)phenol, barbituric acid, 1-methyl 2-pyrrolidinone hydrazonehydrochloride, quinoxaline, 1-ethyl-4-piperidone, 1-ethylpiperazine, orethyl 2-picolinate.
 18. A method as in claim 14, wherein theheterocyclic compound includes at least one heteroatom selected from anoxygen atom, a nitrogen atom, or both.
 19. A method for manufacturing acarbon nanomaterial dispersion, comprising, (i) providing a carbonnanomaterial comprising a plurality of multi-walled, graphitic carbonnanospheres having an aspect ratio of less than about 3:1, wherein theplurality of carbon nanospheres are at least partially agglomerated intoa plurality of clusters of carbon nanospheres; (ii) providing an organicsolvent comprised of a heterocyclic compound; and (iii) mixing thecarbon nanomaterial with the solvent to form a mixture andultrasonicating the mixture to at least partially disrupt theagglomeration of the carbon nanospheres to yield carbon nanospheressuspended in the organic solvent.
 20. A method as in claim 19, whereinthe organic solvent comprises at least one of methylpyrrolidone (NMP),pyridine, 1-(3 aminopropyl)imidazoles, 1-diethoxy methyl imidazoles, 1-2(hydroxyethyl)imidazoles, 4(1H-imidazole-1-yl)aniline, 4(imidazole1-yl)phenol, barbituric acid, 1-methyl 2-pyrrolidinone hydrazonehydrochloride, quinoxaline, 1-ethyl-4-piperidone, 1-ethylpiperazine, orethyl 2-picolinate.